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CO 2 -derived methanol is an attractive raw material for biobased production of value-added chemicals. Here, we investigated the native methylotrophButyribacterium methylotrophicum, which could synchronously assimilate methanol and CO 2 to butyric acid anaerobically. Supplementation with an approximate amount of bicarbonate could improve methanol metabolism of B. methylotrophicum, and 2.04 g/L butyric acid was finally obtained from 100 mM methanol and 20 mM bicarbonate. The genes involved in methanol metabolism were further identified through homologous alignment and transcriptome analysis. The methyltransferase cluster along with genes of the carbonyl branch of the Wood−Ljungdahl pathway (WLP) was found to be transcriptionally activated for the assimilation of methanol and CO 2 . To engineer B. methylotrophicum, an efficient electrotransformation protocol and several functional promoters were subsequently developed. Following a systematic investigation of various parameters, the electrotransformation efficiency was increased to 3.2 × 10 3 transformants/μg DNA. The activities of four heterologous promoters including P thl , P araE , P ptb , and P adc were comparatively determined. With these genetic toolkits, transformants overexpressing genes associated with methyltransferase system or butyric acid synthesis were obtained, where methanol consumption was increased by 16.9 and 14%, and butyric acid production was increased by 13.8 and 28.6%, respectively, in methanol and CO 2 medium. These results exhibit the great potential of B. methylotrophicum as a chassis for C1 bioconversion.

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China's average household saving rate is one of the highest in the world. One popular view attributes the high saving rate to fast-rising housing prices and other living costs in China. This article uses simple economic logic to show that rising housing prices and living costs per se cannot explain China's persistently high household saving rate. Although borrowing constraints and demographic changes can help translate housing prices to the aggregate saving rate, quantitative simulations using Chinese data on household income, housing prices, and demographics indicate that rising mortgage costs contribute at most 5 percentage points to the Chinese aggregate household saving rate, given the down payment structure of China's mortgage markets. (JEL D14, D91, E21, I31, R21)

Pendant drop method has been used to measure the equilibrium interfacial tension and dynamic interfacial tension of CO2/crude oil system under the simulated-formation condition, in which the temperature is 355.65 K and pressure ranges from 0 MPa to 30 MPa. The test results indicated that the equilibrium interfacial tension of CO2/crude oil systems decreased with the increase of the systematic pressure. The dynamic interfacial tension of CO2/original oil, CO2/remaining oil, and CO2/produced oil systems is large at the initial contact and decreases gradually after that, and then finally it reaches dynamic balance. In addition, the higher the pressure is, the larger the magnitude of changing of CO2/crude oil interfacial tension with time will reduce. Moreover, by PVT phase experiment, gas-oil ratio, gas composition, and well fluid composition have been got, and different contents of light components in three oil samples under reservoir conditions have also been calculated. The relationship between equilibrium interfacial tensions and pressures of three different components of crude oil and CO2system was studied, and the higher C1is, the lower C2–C10will be, and the equilibrium interfacial tension will get higher. Therefore, the effect of light weight fractions on interfacial tension under formation conditions was studied.

Tight oil is an important and potential reservoir in future China. Drawn from the successful exploration of tight oil in North America, tight oil exploration is now in progress in China. In this paper, we surveyed the tight oil exploration status and challenges, as well as the tight reservoir properties in China, including source rocks, lithology, physical properties and pressure coefficient. The process of pilot test and key technologies are analyzed, while it is still urgent to improve tight oil study and the production mode. We concluded that there are 4 aspects, which are geological features, energy supplement for formation, engineering and technical management innovation, should be improved, and national policy support for tight oil is another key point for successful exploration.

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